Project Summary/Abstract If finalized, the FDA's proposed Deeming Rule would extend FDA's regulatory authority to e-cigarettes and other tobacco products, allowing FDA to propose rules that restrict their advertising and promotion. Any potential marketing restrictions FDA may impose on e-cigarettes in future are required by law to be based on the scientific evidence demonstrating the population-level impact of such measures. Unfortunately, to date, no studies have examined the population level impact of televised e-cigarette advertising. This project will advance the scientific knowledge on e-cigarettes by filling this critical research gap. The overarching goal of this project is to examine the direct effects and the unintended consequences of televised e-cigarette advertising and provide timely scientific bases for FDA's Deeming Rule and any future potential regulatory actions on restricting marketing for Electronic Nicotine Delivery Systems (ENDS). The specific aims are: 1) to examine the impact of e-cigarette TV advertising on awareness, risk perceptions, intentions to use, initiation, and patterns of use of e-cigarettes and combustible cigarettes. 2) to assess the unintended consequences of e-cigarette TV advertising, examining a) its impact on attitudes, beliefs, and behaviors related to other ENDS products such as vaping pens, e-hookah, tank-style e-cigarettes/Mods, and vaping juice; b) substitution away from evidence-based cessation methods among smokers; and c) its impact on risk perceptions about vaping marijuana, intentions to vape, initiation, and marijuana vaping; and 3) to study whether/to what extent state and local tobacco control policies and policies restricting e-cigarette and marijuana use modify the direct effects and unintended impacts of e-cigarette TV advertising. These aims will be accomplished by applying proven research and analytic methods to a unique combination of new survey data and existing data collected via previously NIH-funded projects led by the proposed research team. The findings from this project will provide highly policy-relevant and timely scientific evidence on the population level impact of e-cigarette TV marketing. This project holds the potential to provide unique insight into e-cigarette TV advertising's direct effects and unintended influences on attitudes, beliefs, and behaviors related to a wide spectrum of ENDS and vaping products.